Tissue engineering and organ transplantation are principally concerned with the replacement of tissue and organs that have lost function due to injury or disease. In one approach toward this goal, organs are transplanted into a patient. However, the side effects of transplantation can be unpleasant, and can compromise the health of the organ recipient. In another approach, cells are cultured in vitro on biodegradable polymeric scaffolds to form tissues or neo organs that are then implanted into the body at the necessary anatomical site.
Several techniques have been proposed for forming scaffolds for tissue growth. For instance, U.S. Patent Publication No. 2002/0182241, entitled “Tissue Engineering of Three-Dimensional Vascularized Using Microfabricated Polymer Assembly Technology,” by Borenstein et al., describes two-dimensional templates that are fabricated using high-resolution molding processes. These templates are then bonded to form three-dimensional scaffold structures with closed lumens. U.S. Pat. No. 6,176,874, entitled “Vascularized Tissue Regeneration Matrices Formed by Solid Free Form Fabrication Techniques,” by Vacanti et al., describes solid free-form fabrication methods used to manufacture devices for allowing tissue regeneration and for seeding and implanting cells to form organ and structural components. U.S. Patent Publication No. 2003/0069718, entitled “Design Methodology for Tissue Engineering Scaffolds and Biomaterial Implants,” by Hollister et al., describes anatomically shaped scaffold architectures with heterogeneous material properties, including interconnecting pores.
Despite the above efforts, significant developments in connection with many internal, physical structures, especially those of hollow and epithelial organs, has been limited, and improvements are needed.